Large Cell Carbon Core Sandwich Panel Sag Prevention

Solution Overview

Problem

The manufacturing of large cell carbon core sandwich panels requires multiple cure cycles and separate tooling due to sagging, permeability, and dimpling issues with uncured laminates, which complicates the process and increases costs.

Innovation Solution

The method involves pressurizing the cells within the carbon core to prevent laminate sagging during curing, using a port to introduce gas and create an airtight core pocket, allowing for co-curing of laminates and core in a single cycle, thereby eliminating sagging and permeability issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uncured laminates are used in large cell carbon core panels, then the panel can be manufactured, but the laminates sag into the cells creating permeability and dimpling

Engineering Contradiction:

Improvemanufacturability of large cell carbon core panelVSAvoidsurface quality and integrity of laminate

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The core is pre-pressurized with gas before the laminates are cured, creating a supportive pressure field that prevents the uncured laminates from sagging into the cells during the curing process. This preliminary action of pressurization occurs before the harmful sagging effect can manifest.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Gas is introduced into the core cells through a port to create internal pressure that counteracts the gravitational and curing forces causing laminate sag. The pneumatic pressure within the cells provides continuous support to the uncured laminates throughout the curing cycle.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Device complexity

If traditional single curing process is used, then manufacturing is simplified, but uncured laminates sag into large cells creating permeable and dimpled panels

Engineering Contradiction:

Improvemanufacturing process complexityVSAvoidstructural integrity of panel

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The core is pre-pressurized with gas before the laminates are cured, creating a supportive pressure field that prevents the uncured laminates from sagging into the cells during the curing process. This preliminary action of pressurization occurs before the harmful sagging effect can manifest.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Gas is introduced into the core cells through a port to create internal pressure that counteracts the gravitational and curing forces causing laminate sag. The pneumatic pressure within the cells provides continuous support to the uncured laminates throughout the curing cycle.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Manufacturing precision

If pre-cured laminates are used to avoid sagging, then panel integrity is maintained, but three separate cure cycles and tooling sets are required

Engineering Contradiction:

Improvesurface quality and integrity of laminateVSAvoidmanufacturing efficiency and cost

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The core is pre-pressurized with gas before the laminates are cured, creating a supportive pressure field that prevents the uncured laminates from sagging into the cells during the curing process. This preliminary action of pressurization occurs before the harmful sagging effect can manifest.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Gas is introduced into the core cells through a port to create internal pressure that counteracts the gravitational and curing forces causing laminate sag. The pneumatic pressure within the cells provides continuous support to the uncured laminates throughout the curing cycle.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables the production of large cell carbon core sandwich panels with improved structural integrity and simplified fabrication, reducing the number of cure cycles and tooling requirements, while maintaining a smooth inner surface.

Implementation Method 1

pressurizing the cells within the carbon core to prevent the laminates from sagging into the cells during the curing process

Methodology Applied

Scientific EffectGas pressure: Pressure Increase

Implementation Method 2

using a port to introduce gas and create an airtight core pocket

Methodology Applied

Scientific EffectGas containment: Physical Containment

Data Source

PatentUS11712871B2Large cell carbon core sandwich panel and method of manufacturing same

Publication Date: 2023.08.01 TEXTRON INNOVATIONS INC

AI summary

A method of fabricating a panel includes laying up a first laminate on a tooling surface, laying a first layer of thermoplastic on an inner surface of the first laminate, laying a large cell carbon core on the first layer of thermoplastic, laying a second layer of thermoplastic across the large cell carbon core, laying a second laminate on the second layer of thermoplastic, creating a sealed core pocket by bonding the edges of the first and second layers of the thermoplastic surrounding a perimeter of the core, increasing pressure within the core pocket, increasing pressure on the outer surface of the second laminate, heating the panel to a desired curing temperature, and maintaining the increased pressures and temperature for a desired curing duration.